The invention concerns an electrodynamic transducer, a diaphragm, a web of sheet having such a diaphragm and a magnet system for the transducer.
The concept electrodynamic acoustic transducer in particular comprises microphones which convert sound signals in the air into electrical signals, and sound generators which convert electrical signals into sound signals in the air. Traditionally, such transducers have a ring-shaped, wound coil of copper wire which is present in a ring-shaped air gap having a radially oriented magnetic field. Such coils are wound on automatic winding machines, and then the coils are to be mounted on a diaphragm, e.g., by gluing. After their manufacture on a winding machine, the coils and in particular their thin copper wires are vulnerable, and they must therefore be handled with great care in order not to be damaged and with great accuracy. The coils are to be mounted on the diaphragms with narrow tolerances, and also the diaphragm with the mounted coil is to be placed very precisely in the magnetic circuit.
It is increasingly required that microphones to be used in portable telephones shall have small physical dimensions, and it is simultaneously desired that such a small microphone is to have a sensitivity which is comparable to the sensitivity of a traditional, larger microphone. These requirements clash with each other, one reason being that a small diaphragm is less resilient than a corresponding larger diaphragm, and a small diaphragm therefore moves correspondingly less at the same sound pressure than a large diaphragm, which results in a smaller electrical output signal.